Automatic circuit breaker



ug. 6, 1940. ,1 SACHS 2,210,260

AUTOMATIC CIRCUIT BREAKER Filed Feb. 27, 1939 Patented Aug. 6, 1940UNITED STATES PATENT OFFICE AUTOMATIC CIRCUIT BREAKER necticutApplication February 27, 1939, serial No. 258,098

11 Claims.

This invention relates to a circuit breaker of the type set forth in myreissued Patent No. 20,018 and in my Patents Nos. 1,812,843, 2,020,333and 2,094,063 all entitled Automatic circuit breaker.

Each of the circuit breakers disclosed in the before-mentioned patentsincludes a bodily movable bi-metallic element or strip which serves inand of itself as a latch to normally hold the movable contact member inclosed-circuit position, the movable contact member being ordinarilyconnected by means of the said latch with a manually operable actuatorso that the said actuator can move the contact member for ordinaryswitching purposes. The bi-metallic latch is so arranged that it isheated upon the attainment of excess current conditions in the circuitso that it is deflected in s uch a way as to be released or disengaged,the contact member thereupon being permitted to move automatically toopen-circuit position independently oi the actuator.

One of the objects of the present invention is to provide a circuitbreaker of the general type disclosed in the said patents, but soconstructed that the bodily movable bi-metallic strip is entirelyrelieved of any mechanical stresses resulting from the holding or themoving of the movable contact member. This object is attained byproviding a mechanical latch for effecting the moving and the holding ofthe contact member, the said latch being functionally independent of themovable bi-metallic element or strip butassocated therewith in such away that the said strip upon being heated and deflected causes the latchto be released so as to thus permit the Contact member to automaticallymove to open-circuit position.

Another object of the invention is to provide in association with theindependent mechanical latch before referred to, a means entirelyindependent of the bodily movable bi-metallic strip' for also moving thelatch to cause the release thereof. This separate means may b e a magnetconnected in the circuit so as to operate upon attainment of excesscurrent conditions. When a bi-metallic strip and a magnet are bothprovided, they may be so designed that the bimetallic strip will beslowly heated and deected as the result of a long continued overload andthat the magnet will be instantaneously energized upon a heavy overloadsuch as a short circuit. It willbe understood that in accordance withthe present invention, the movable bimetallic latch and the magnet actindependently of each other upon the separate mechanical latch, thisconstruction being distinctly different from that shownin my aforesaidReissued Patent No. 20,018 wherein there is provided a magnet which actsto cause or at least augment the deection of the bi-metallic strip.

In the accompanying drawing I have shown the embodiment of the inventionwhich I now deem preferable, but it will be understood that the drawingis intended for illustrative purposes only and is not to be construed asdelining or limiting the scope of the invention, the claims forming apart of this specication being relied upon for that purpose.

Of the drawing: Fig. 1 is a front view of a circuit breaker embodyingthe invention, the front cover being omitted.

Fig. 2 is a vertical sectional view taken along the line 2 2 of Fig. 1.In this view the front cover is included.

Fig. 3 is a transverse horizontal sectional view taken along the line3-3 of Fig. 5.

Fig. 4 is a vertical sectional view taken along the line 4 4 of Fig. 1,this view also showing the front cover of the circuit breaker which isin sectionvalong the central vertical plane thereof. In this view theoperating parts are shownin opencircuit positions.

Fig. 5 is a View similar to the Fig. 4 but omitting the front cover andshowing the operating parts in closed-circuit positions.

Fig. 6 ls a view similar to Fig. 5 but showing the operating parts inthe positions which they assume when automatic opening takes place withthe handle or operating member held in its' of which the entire circuitbreaker can be mounted in a wall box or other suitable casing. A

The main base or casing I has an opening or recess at the front and isclosed or substantially closed at the rear. A lfront guide plate 1 isprovided which substantially closes the front opening in the casing I.Resting upon the guide plate 'l are two conducting members 8 and 9 whichare similar in construction except that they are extend forward throughthe casing I and through holes in the plate 1. The .screws thus servenot only to hold-the members 8 and 9 but also to hold the`plate 1.

The^member 8 lis somewhat shorter than the member 9, and immediatelybelow the said member 8, but insulated therefrom, is a wire terminal I4,held by a threaded tube I5 and a screw I6. The member 9 is -providedwith aA corresponding wire terminal I1 at 'the lower end thereof. Thecover 2 is provided with notches 2a at the lower corners to providespace for the terminals I4 and I1.

The members 8 and 9 are provided with rearward extending portions l!aand 9a which are positioned in suitably formed notches in the sides ofthe plate 1. Carried by and electrically connected with the saidportions 8a and 9a are resilient conducting elements I8 and I9 .whichcarry contacts'28 and 2I. The said contacts 28 land 2| are stationaryexcept for such movement as is provided by the resiliency of theirsupports I8 and I9 and they will be hereinafter referred to asstationary contacts. v

The members 8 and 9 are provided withforward projecting ears 8b and 9'Jwhich serve to support a pivotally mounted handle 22. The handle isprovided with hubs 22a having axially positioned vpintles .2 3 seated inbearing apertures in the said ears 8b and 9b. The cover 2 has forwardtending transversely-between the two side plates and 'associated withthe contacts is an insulating 'is preferably formed of insulatingmaterial and it carries a metallic'piece 25 adapted to be connected withoperating links to be hereinafter described.

The contact carrying` member of the circuit breaker is rectilinearlymovable within the hollow interior of the casing I, the said memberbeing guided at the front and heldin place by means of thebefore-mentioned guide plate 1. The said contact-carrying memberpreferably .comprises two insulating plates 26 and 21 which are spacedapart transversely. The two plates 26 and 21 are adapted to engage -atthe front directly with the guide plate 1. At the rear there ispreferably provided an auxiliaryguide plate 28 seated in the bottom ofthe main recess in the casing I.

Two laterally projecting movable contacts 29 and 38- are carried bythe'contact member at the sides thereof, these contacts projectinglaterally from the respective side plates 26 and 21 and b el ing adaptedto be engaged' with and disengaged The two movable contacts 29 and 38are electrically connected with each other, this electrical connectionAbeing through a -bodily movable bimetallic lJl-shaped thermostaticstrip 32, mechanically .and electrically connected directly with the twocontacts.

From" the foregoing descriptionit will be ap-v parent that the contactmember is movable rectilinearly as guided by the plates 1 and 28, andthat in so moving it serves t'o bring the movable contacts 29 and 38into or out of engagement with the respective stationary contacts 28 and2l to make or break the circuit. When the contact member is in the uppercontact engaging position as shown in Figs. 2 and 5, electricalconnection is established between the conducting members 8A rear ofthecasing I.

Preferably vand as shown For actuating the contact member for normalswitching purposes, or to effect closing ofthe circuit after automaticopening thereof, I provide a member 34 which I shall term an actuatingmember or actuator. The actuator is pivoted to the contact member formovement about atransverse axis in fixed relationship thereto. Theactuating member 34 is of bell crank form and consists of a metallicplate pivotally mounted on a pin 35 .ex-

tending transversely between the two side plates v26 and 21. Spacingbushings 36, 36 hold the actuator in central position. A shoulder 34 onthe actuator 34 is adapted to engage the plate 1 and to thus limitrelative movement of the actuator inA the clockwise direction. Theactuator'is provided with a tooth 34b which is normally engagedv by awear piece carried by a latch 31 pivoted on a pin 38 extendingtransversely between the side plates 26 and 21. Aspring 39 biases thelatch for clockwise. movement and such movement is limited bystop pins48, 48. The latch is immediately adjacent the bi-metallic stripV 32, sothat upon rearward deflection of the strip the latch is cor respondinglymoved. With the parts in the relative positions shown in Fig. 5, theactuator and the vcontact member are positivelyconnected by the latch 31so as to move in unison.

The handle or operating member 22 serves as the means for manuallyoperating the actuator 34. The metallic piece 25 on the handle member 22is connected with the actuator 34 by means of 'two similar links 4I, 4I,the links being pivoted to the handle at 42 and to the-actuator at 43.

When the parts are in the relative positions shown in Fig. 5 the links4I cooperate with the handle 22 to form a togglewhich locks the parts inposition with the movable contacts 29 and 38 pressed into firmengagement with the stationary contacts 28and 2l. Continued movement ofthe handle in the counter-clockwise. direction is prevented by theengagement of an extension25a on the metallic piece 25 with the frontguide plate 1 as shown in Fig. 5. Ihe pivotal axis at 42 is at the leftof a straight line connecting the pivotal -axes at 23 and43,and thus thehandle member 22 and the links -4I serve to resist the tendency of thecontact member to move downward under the influence of the Aspring 33and of gravity.

The spring 33 is sufliciently. powerful to enable the said toggle actionto hold the handle or oper- `leased by pressing the handle upward, theparts then moving under theaction of the'sprlngs 33 and 24 totheopen-circuit position. shown in Fig.

4. The movable contacts 29 and 30 are thus disengaged from thestationary contacts 20 and 2l and the circuit is broken in two separateplaces. By moving the handle toward the downward position the severalparts can be restored to their respective closed-circuit positions, asshown in Fig. 5, and the circuit can be thus re-established.

As before explained, the bi-metallic strip 3 is electrically connectedbetween the movable contacts 23 and 30. It is adapted to be deflectedrearward upon the passage of excess current therethrough, with theresult that the latch 31 is moved rearward so as to be disengaged fromthe tooth 34b of the actuator 34. Such disengagement permits theactuator 34 to turn slightly relatively to the contact member in thecounterclockwise direction. This slight movement changes the relation ofthe toggle links 4l and 22 and reduces the pressure which hadtheretofore served to hold the links 4I iand the handle member 22 intheir effective toggle relationship. This change in relationship andreduction in pressure permits the handle member 22 to move in theclockwise direction so as to render the toggle ineffective. Thus boththe contact member and the handle are freed and both of them move totheir open-circuit positions under the influence of their respectivesprings. It will be understood that normally the contact member and thehandle move substantially simultaneously with the result that the latchand the actuator may never be substantially separated from each other.When the parts reach their full open-circuit position as shown in Fig. 4the latch and the actuator are in position to fully re-engage as soo'nas the thermostatic strip is suiiiciently cooled.

The circuit-opening movement of the contact member is not in any waydependent on the circuit-opening movement of the handle member and will,in fact, occur even though the handle member be held in itsc-losed-circuit position, as shown in Fig. 6. The rearward deection ofthe thermostatic strip 32 releases the latch and permits the actuator 34to turn in the counterclockwise direction as already stated, even thoughthe handle is held, thus releasing the contact member from the controlof theA handle member 22 and of the links 4l. The contact member movesdownward to the position shown in Fig. 6, the actuator 34 and the links4i assuming the relative positions shown in that figure. If the handle22, after having been held as described, be now released, it will moveunder the influence oi the spring 24 to its open-circuit position asshown in Fig. 4, thus bringing the actuator 34 into its normal positionwith respect to the contact member so that the tooth 34b isautomatically engaged by the latch 31.

It will be observed that with the described construction, thebi-metallic strip 32 is entirely free from any stresses resulting fromthe holding or moving of the contact member. All such stresses arecarried solely by the mechanical latch 31 and the bi-rnetallic stripserves merely as a means for moving the latch.

It may be desirable, and sometimes preferable, to provide a meansadditional to the bi-metallic strip 32 for also moving the latch 31 toeffect release thereof to thereby effect opening of the circuit. While Ido not necessarily limit myself as concerns the character of thisadditional means, I prefer for this purpose, and have shown, a magnet44. This magnet is located in a suitable recess in the rear wall of thebase l and is adjacent the closed-circuit position of the latch 31 asclearly shown in Fig. 5. The latch 31 is provided with an armature 45for cooperation with the magnet, the armature being drawn rearward whenthe magnet is energized, thus moving the latch rearward and effectingits release from the actuator 34. The circuit is then opened in themanner already described.

The magnet 44 may be electrically connected in any suitable way, butpreferably it is connected in the main circuit of the breaker and inseries with the contacts and with the 'ni-metallic strip 32. As shown,particularly in Fig. 7, wires 4S and 41 connect the magnet respectivelywith the screws lil and I6, these wires being positioned in suitablegrooves 48 and 49 formed in the rear wall of the base i,

Preferably the electrical characteristics of the bi-metallic strip 32and of the magnet 44 are such that a low overload which will notenergize the magnet sutliciently to release the latch will, ifcontinued, cause the gradual heating and deflection of the strip 32 soas to eventually release the latch 31 in the manner already described.However, in the event of a heavy overload or short circuit, the magnet44 will be instantaneously energized thus immediately releasing thelatch without the delay which would be involved in the heating anddeflection of the bi-metallic strip 32.

What I claim is:

l. In an automatic circuit breaker, the combination of a stationarycontact, a movable contact member having acontact adapted to engage and'disengage the stationary contact, the said contact member being biasedfor movement toward its open-circuit'position, a thermostatic bimetallicstrip supported upon and bodily movable with the contact member andarranged to be heated and deflected upon the attainment of an abnormalcurrent condition in the circuit, and means including a releasable latchbodily movable wlth the contact member and normally servingindependently of the bi-metallic strip to hold the contact member inclosed-circuit position, the said latch beingautomatically released upondeflection of the strip so as to thus permit the contact member toautomatically move to opencircuit position.

2. In an automatic circuit breaker, the cornbination oi a stationarycontact, a movable contact member having a contact adapted to engage anddlsengage the stationary contact, the said contact member being biasedfor movement toward its open-circuit position, a thermostatic bimetallicstrip supported upon and bodily movable with the contact member, thesaid strip being connected in the circuit so as to be heated anddeflected upon the attainment of an abnormal current condition in thecircuit, and means including a releasable latch bodily movable with thecontact member and normally serving independently of the lai-metallicstrip to hold the contact member in closed-circuit position, the saidlatch being automatically released upon deection of the strip so as tothus permit the contact member to automatically move to open-circuitposition.

3. In an automatic circuit breaker, the combination of a stationarycontact, a movable contact member having a contact adapted to engage anddisengage the stationary contact, the said contact member being biasedfor movement toward its open-circuit position, a thermostatic bimetalllcstrip supported upon and bodily movable with the contact member and`arranged to be heated upon the attainment of an abnormal currentcondition in the circuit and thus deected, and means including areleasable latch bodily movable with the contact memberand normallyserving independently of the bi-metalllc strip to hold the contactmember in closed-circuit position, the said latch being directly engagedby the strip and being automatically moved thereby upon deection thereofso as to thus permit the contact member to automatically move toopencircuit position.

4. In an automobile circuit breaker, the combination of a stationarycontact, a movable contact member having a contact adapted to engage anddisengage the stationary contact, the said contact member being biasedfor movement toward its open-circuit position, `an actuating membermovable under manual control, a thermostatic bi-metallic strip supportedupon and bodily movable with the contact member and arranged to beheated and deflected upon the attainment of an abnormal currentcondition in the circuit, and means-including a releasable latch bodilymovable with the contact member and normally serving independently ofthe bimetallic strip to connect the contact member with the actuatingmember so that the latter may move the former and hold it inclosed-circuit position, the said latch being automatically releasedupon deflection of the strip so as to thus permit the contact member toautomatically move to open-circuit position free from the conn trol ofthe actuating member.

5. In an automatic circuit breaker, the combination of a stationarycontact, a rectilinearly movable contact member having a contact adaptedto engage land disengage the stationary contact, the said contact memberbeing biased for movement toward its open-circuit position, an actuatingmember rectilinearly movable under manual control, a thermostaticbi-metallic strip supported upon and bodily movable with the contactmember and extending approximately in the direction of rectilinearmovement, the said strip being arranged to be heated and deilected uponthe attainment of an abnormal current condition in the circuit, andmeans including a releasable latch bodily movable with the contactmember and normally serving independently of the bi-metallic strip toconnect the contact member with the actuating member so that the lattermay move the former and hold it in closed-circuit position, the saidlatch upon deflection of the strip being automatically movedtransversely of the aforesaiddirection of rectilinearmovement and thusreleased so as to thus permit the contact member to automatically moveto open-circuit position free from the control of the actuating member.t

6. In an automatic circuit breaker, the combinationpf a stationarycontact, a movable contact member having a contact adapted to engage anddisengage the' stationary contact, the said contact member being biasedfor 'movement toward its open-circuit position, an actuating membersupported upon and bodily movable with the contact member and alsomovable relatively thereto, manually operable means for moving theactuating member, a thermostatic bimetallic strip supported upon andbodily movable with the contact member and arranged to be heated anddeflected upon the attainment of an abnormal current condition in the=circuit, and means including` a releasable latch bodily movable with thecontact member and normally serving independently of the Ibi-metallicstrip to connect t@ contact member with the actuating member to preventmovement of the latter relatively to the former and thus enable theactuating member to move the contact member and hold it inclosed-circuit position, the said latch being automatically releasedupon deection-of the strip and thus permitting the contact member toautomatically move to opencircuit position free from the control of theactuating member. l

"7. In an automobile circuit breaker, the com bination of a stationarycontact, a 'movable contact member having a contact adapted to engageand disengage the stationary contact, the said contact member beingbiased for movement toward its open-circuit position, a thermostaticbi-metallic strip supported upon and bodily movable with the contactmember and arranged to be heated and deiiected upon the'attainment of anabnormal current condition in the circuit, means including a releasablelatch bodily movable with the contact member and normally servingindependently of the bi-metallic strip to hold the contact member inclosed-circuit position, the said latch being automatically releasedupon deflection of the strip so as to thus permit the contact member toautomatically move -to :open-circuit position, and means additional tothe bi-metallic strip/and acting independently thereoffor releasing thelatch.

8. In an automatic circuit breaker, the combination of a stationarycontact, a movable contact member having a contact adapted to engageandv disengage the stationary contact, the said contact member beingbiased for movement toward its open-circuit position, a thermostaticlbi-metallic strip supported upon and bodily movable with the contactmember and arranged to be heated and deected upon the attainment of anabnormal current condition in the circuit, means including a releasablelatch bodily movable with the contact member and normally servingindependently of the bi-metallic strip to hold the contact member inclosed-circuit position, the said latch being automatically releasedupon deflection of the strip so.as to thus permit the contact member toautomatically move to open-circuit position, and a magnet connected inthe circuit and serving upon the attainment of excess current conditionsin the circuit to moveA and release the latch entirely independently ofthe bi-metallic strip.

9. In an automatic circuit breaker, the combination of a stationarycontact, a movable contact member having a contact adapted to engage anddisengage the stationary contact, the said contact member being biasedfor movement towardy its .A

open-circuit position, a thermostatic bl-metallic strip supported uponand bodily movable with the contact member and arranged to be heated anddeflected upon the attainment of an abnorary and located adjacent theclosed-circuit position of the latch.

10. In an automatic circuit breaker, the combination of a stationarycontact, a movable contact member having a contact adapted to engage anddisengage the stationary contact, the said contact member being biasedfor movement toward its open-circuit position, an actuating membermovable under manual control, a thermostatic bi-metallc strip supportedupon and bodily movable with the contact member and arranged to beheated and deilected upon the attainment of an abnormal currentcondition in the circuit, means including a releasable latch bodilymovil.-` ble with the contact member and normally serving independentlyof the bi-metallic strip to connect the contact member with theactuating member 'so that the latter may move the former and hold it inlclosed-circuit position, the said latch being automatically releasedupon deflection of the strip so as to thus permit the contact member toautomatically move to open-circuit position free from the control of theactuating member, and means additional tothe bi-metallic strip andacting independently thereof for releasing the latch.

11. In an automatic circuit breaker, the combination of a stationarycontact, a movable contact member having a contact adapted to engage anddisengage the stationary contact, the vsaid contact member being biasedfor movement toward its open-circuit position, an actuating membermovable under manual control, a thermostatic bi-metallic strip supportedupon and bodily movable with the contact member and arranged to beheated and deflected upon the attainment of an abnormal currentcondition in the circuit, means including a releasable latch bodilymovable` with the contact member and normally serving independently ofthe bi-metallic strip to connect the contact member with the actuatingmember so that the latter may move the former and hold it inclosed-circuit position, the said the latch entirely independently ofthe bi-metaly lic strip.

JOSEPH SACHS.

